Life cycle assessment of wood-based heating in Norway
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Background, aim, and scope
In this study, we evaluate the environmental effects of wood-based household heating. Wood is a significant source of household heating in Norway, and a comparative life cycle assessment of a wood-based heating system using an old and a modern stove was conducted to estimate the total life cycle benefits associated with the change from old to new combustion technology.
Materials and methods
The study uses a new approach to complete the inventory. Input–output data are used in combination with the Leontief price model to estimate inputs of products and services from the background economy to the birch wood supply chain.
When comparing new and old stove technology, the results show that the new technology contributes to a significantly improved performance (28–80%) for all types of environmental impact studied. As there is a large share of old wood stoves still in use, replacing the old stoves with new ones can lead to substantial reductions in environmental impacts, especially impacts affecting human health. The use phase, i.e., wood combustion, is responsible for over 60% of the impact within all categories. Both the old and new stove provide heating with emissions of greenhouse gases ranging from one third (new stove, ∼80 g CO2-eq/kWh) to half (old stove, ∼110 g CO2-eq/kWh) of the impacts compared to electricity use from the Nordic electricity mix (∼210 g CO2-eq/kWh) to heat the house.
Combustion of the wood is found to be most important for all types of impacts, even for global warming, where the CO2 emissions from combustion are treated as “climate neutral.” Products of incomplete combustion are the reason for this, as well as the high contribution to other impact categories. Emission factors for these substances are subject to high uncertainty. Although the combustion phase is the most important stage in the life cycle, transportation distances can play an important role. To render wood as environmentally benign as possible, one should thus seek to shorten the distances from producer to consumer.
There is a significant difference in the life cycle performance of a wood stove using modern technology versus older technologies within all impact categories. In addition, there is a preference to use locally produced firewood over wood transported over long distances.
Recommendations and perspectives
A strong emphasis on phasing out old woodstoves should be maintained and is well justified.
KeywordsBirch wood Household heating LCA Norway Wood-based household heating Wood stove
The authors would like to thank Edvard Karlsvik (SINTEF), Libjørk, Skogforsk, and Harpreet Singh Kandra for various contributions to this study.
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